Many types of devices are produced by manufacturers, and various methods have been developed for testing, troubleshooting, and/or otherwise ensuring the proper operation of such devices. Often, various devices are manufactured as “modules” that are then combined to form a larger system. For example, various paper handling modules, such as modules for sorting, stacking, stapling, etcetera, are commonly combined into a larger system, such as a photocopier. As another example, various automotive modules, such as an engine, transmission, radiator, brake system, etcetera, are commonly combined into a larger system forming an automobile.
Generally, analysis of the operation of devices may include optical analysis. For instance, optical sensors may be utilized in developing a device to enable monitoring of the device's operation, such as detection of movement of internal parts of the device. Consider, for example, a paper handling device, such as a paper sorter, may include various levers and optical switches (sensors) arranged to detect when each lever opens and closes. For instance, as paper travels through the paper handling device, the paper may cause various levers to open and close along the way. More specifically, as the leading edge of a sheet of paper progresses through a segment of the paper handling device, it may lift a lever, which in turn interrupts an optical switch, and as the trailing edge of the sheet passes through the lever, the lever closes, which ends the interruption of the optical switch. Electrical signals may be communicated from the optical sensor to a computer to compute the timing for the sheet passing through the lever. Such optical analysis is typically performed during development stages of a device, rather than production (or manufacturing) and/or post-production stages, to aid a developer in designing devices with proper timing.
During production and/or post-production of a device, various forms of manual analysis of the device's operation may be utilized. For example, at various stages of production of a device, a user may visually inspect the device. Additionally, once the device is completed, a visual inspection of the device may be made during operation to ensure that the device appears to function properly. For some devices, various forms of robotic testing/analysis may also be performed. For instance, software code intended to test the operation of a microprocessor may be loaded for execution by a microprocessor to allow for testing/analysis of the microprocessor.
As described above, some systems are formed by combining various modules. Often, the individual modules are tested/analyzed before being combined into a larger system to ensure that each module satisfies predefined operational criteria established for such module. However, even though each module may satisfy its predefined operational criteria, when combined with other modules to form the larger system, such modules may result in deteriorated performance of the system. For instance, if two modules are near their threshold tolerances for acceptable performance, they may individually be acceptable, but may result in deteriorated performance when combined. For example, a first paper handling module may have a predefined timing criteria that its operation must satisfy, and a second paper handling module may have a different timing criteria that its operation must satisfy. For instance, suppose a first paper handling module must pass a sheet of paper through a particular lever at a rate between 670 milliseconds (ms) and 730 ms. A rate of 700 ms may be the optimum rate for the first paper handling module, but any rate between 670 ms and 730 ms is deemed to be acceptable. A second paper handling module may have a criteria specifying that it must pass a sheet of paper through a particular lever at a rate between 760 ms and 840 ms, with 800 ms being the optimum rate.
Suppose now that one of the first type of paper handling device passes a sheet of paper through the particular lever at a rate of 670 ms (e.g., the lower operational threshold defined for the module) and one of the second type of paper handling module passes a sheet of paper through the particular lever at a rate of 840 ms (e.g., the upper operational threshold defined for the module). Each of the paper handling devices are deemed acceptable because they each satisfy their individual operational criteria. However, once the modules are combined into a larger system, the larger system may not function properly and/or may be unreliable in its operation because each of the modules are at their operational thresholds. Further, the life expectancy of the resulting larger system (i.e., the period of time that it will function properly) may suffer. Thus, such modular testing of devices may fail to give an accurate analysis of the performance of the overall system. Additionally, determining the cause of improper operation of the resulting system may be difficult, especially if operational problems occur sporadically, because each module was individually tested and found to satisfy its predefined operational criteria (e.g., because each individual module was determined to be acceptable, it may be difficult to determine the cause of failure when the modules are combined).
Furthermore, even if analysis, such as the above-described optical analysis to determine the timing of operation of various components (e.g., levers), is performed on the overall system, rather than or in addition to modular analysis, a sufficiently detailed view of the operation of such overall system may not be obtained (or may be very difficult to obtain) through such method of analysis. For instance, within a paper handling device, such optical analysis may be utilized to determine that the timing of such device is outside its predefined range. However, the optical analysis typically fails to identify why such timing is outside of its predefined range. Suppose for instance that a paper handling device includes a lever through which a sheet of paper is to pass within a time range of 670 ms to 730 ms. Further suppose that an optical sensor is utilized to analyze a manufactured one of such paper handling device, from which it is determined that a sheet of paper passes through the lever at a rate of 750 ms. While such optical analysis may show that the device's timing is outside its predefined range, such optical analysis fails to identify whether the incorrect timing is caused by improper operation of the device's motor, too much friction present in the system, or some other cause. Thus, such optical analysis is often of little assistance in determining the root cause of operational problems within a device. Additionally, other forms of analysis, including manual analysis by a technician are often difficult, inefficient, and/or unreliable in determining root cause of operational problems encountered with a device. Many times operational problems occur sporadically within a device. For instance, the above-described optical analysis may detect proper timing within a device for many operational iterations, but the device may fail sporadically. As described above, the optical analysis typically provides no clue as to the cause of the sporadic failure.
Root cause analysis is a problem not only when testing/analyzing devices during the manufacturing stage, but also becomes an issue when operational problems later arise within the devices. For example, a customer may utilize a paper handling device, which over time may begin to encounter operational problems. Determining the cause of such operational problems is often difficult, and such difficulty is often increased in situations where the occurrence of operational problems is sporadic. For instance, the device may appear to operate correctly while a technician is examining its operation, but sporadically encounter performance problems when the technician is not present. A technician is, therefore, sometimes left to guess as to the probable cause of a problem described by a customer and must service the device based on such guess, which may be incorrect, leading to continued performance problems (which may worsen over time) and/or increased cost to the customer. Further, some problems exist in the operation of a device that are not readily noticed by a user when operating the device. Such problems may go unnoticed and continue to worsen or lead to other problems until the device fails to operate properly (in a manner that is noticed by a user). Once the device's operation fails in a manner that is noticeable by a user, the customer may be greatly impacted, whereas if the problem were detected and corrected when initially encountered (at a point in which the problem is not readily noticeably by a user), the device may be serviced to avoid such an impact on the customer.